1. Field of This Invention
This invention relates to a new tridecapeptide with the same effect as gastrin effect, and salts and protected derivatives of the new tridecapeptide, as well as a process for the production of the new tridecapeptide. Further, this invention relates to therapeutic and diagnostic agents which contain the new tridecapeptide and/or its salts.
2. Prior Art
Gastrin, which occurs in nature, causes a stimulation of the secretion activity of the stomach and of the pancreas. Gastrin can be used both as a therapeutic agent for the stimulation of the HCl secretion of the stomach and as a diagnostic agent for the determination of the HCl secretion capacity or for the immunological determination of the gastrin.
As is the case with all natural substances, the problem with gastrin consists in the fact that its isolation from, for example, animal organs is very time consuming and expensive, and succeeds only in achieving minimum yields. Also, the synthesis of gastrin (see Beacham, Nature 209, p 585, 1966) is relatively expensive because of the large number of amino acids which are contained in such peptide.
For this reason, attempts have been made to replace gastrin by some substance which is analogous to gastrin and which has fewer amino acids (pentapeptide, heptapeptide). However such peptides have the disadvantage that, in relation to gastrin, they have comparatively lower activity and are very quickly inactivated by the liver [see U. T. Strunz et al., Gastroenterology, 70, A-83/941, (1976)].
Gregory et al., Gut 15, 683-85 (1974), teaches the naturally occurring tridecapeptide minigastrin, which has a methionine radical in the 11-position.